41 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Milton | 1 | 117,556 | 119,961 | -0.2% | 3,414 | 34 | Township |
| Pittsfield | 2 | 4,008 | 4,168 | -0.79% | 838 | 5 | City |
| Pittsfield | 3 | 3,826 | 4,011 | -1.21% | 101 | 38 | Township |
| Barry | 4 | 1,525 | 1,600 | -1.23% | 40 | 39 | Township |
| Barry | 5 | 1,241 | 1,293 | -0.8% | 867 | 1 | City |
| Griggsville | 6 | 1,227 | 1,293 | -1.29% | 33 | 38 | Township |
| Pleasant Hill | 7 | 1,166 | 1,209 | -0.93% | 31 | 38 | Township |
| Griggsville | 8 | 1,039 | 1,091 | -0.95% | 939 | 1 | City |
| Newburg | 9 | 916 | 955 | -0.97% | 25 | 37 | Township |
| Pleasant Hill | 10 | 897 | 924 | -0.55% | 1,173 | 1 | Village |
| Kinderhook | 11 | 698 | 733 | -1.27% | 18 | 38 | Township |
| Pleasant Vale | 12 | 481 | 503 | -1.23% | 12 | 39 | Township |
| New Salem | 13 | 473 | 494 | -1.25% | 12 | 38 | Township |
| Perry | 14 | 464 | 486 | -1.28% | 12 | 37 | Township |
| Spring Creek | 15 | 460 | 475 | -0.86% | 12 | 37 | Township |
| Montezuma | 16 | 433 | 446 | -0.92% | 13 | 34 | Township |
| Atlas | 17 | 432 | 448 | -0.92% | 7 | 64 | Township |
| Hull | 18 | 370 | 390 | -1.07% | 203 | 2 | Village |
| Martinsburg | 19 | 360 | 375 | -1.37% | 10 | 38 | Township |
| New Salem | 20 | 341 | 345 | 0% | 9 | 36 | Township |
| New Canton | 21 | 319 | 331 | -0.62% | 362 | 1 | Town |
| Perry | 22 | 300 | 312 | -0.66% | 777 | 0 | Village |
| Nebo | 23 | 274 | 279 | -0.36% | 631 | 0 | Village |
| Hadley | 24 | 244 | 250 | -0.41% | 7 | 37 | Township |
| Detroit | 25 | 239 | 243 | -0.42% | 9 | 26 | Township |
| Milton | 26 | 209 | 211 | 0% | 541 | 0 | Village |
| Derry | 27 | 208 | 214 | -0.48% | 6 | 37 | Township |
| Pearl | 28 | 188 | 195 | -1.05% | 8 | 25 | Township |
| Kinderhook | 29 | 182 | 187 | -0.55% | 225 | 1 | Village |
| Baylis | 30 | 160 | 169 | -1.23% | 340 | 0 | Village |
| Chambersburg | 31 | 131 | 136 | -0.76% | 5 | 29 | Township |
| New Salem | 32 | 117 | 119 | 0% | 112 | 1 | Village |
| Rockport | 33 | 109 | 49 | 6.86% | 254 | 0 | CDP |
| Pearl | 34 | 101 | 105 | -0.98% | 67 | 2 | Village |
| Flint | 35 | 93 | 94 | -1.06% | 6 | 15 | Township |
| Detroit | 36 | 76 | 75 | 0% | 303 | 0 | Village |
| Ross | 37 | 53 | 51 | 1.92% | 2 | 27 | Township |
| Levee | 38 | 48 | 52 | -2.04% | 2 | 22 | Township |
| Cincinnati | 39 | 22 | 23 | 0% | 1 | 24 | Township |
| Florence | 40 | 16 | 18 | 0% | 58 | 0 | Village |
| Valley City | 41 | 13 | 13 | 0% | 48 | 0 | Village |
Milton is the largest city in Pike County, with a population of 117,556.
Valley City is the smallest city in Pike County, with a population of 13.
There are 41 cities in Pike County, Illinois.